Ferrite sintered bodies formed of Fe—Zn—Ni—Cu-based ferrite materials are widely used as cores of inductors, transformers, stabilizers, electromagnets, noise filters and the like.
Particularly, for electric cars, hybrid cars and the like in which a large number of highly complicated and densified electronic control circuits are mounted, a large number of noise filters using ferrite sintered bodies formed of Fe—Zn—Ni—Cu-based ferrite materials as the cores are used as a measure against noise.
As an example of such Fe—Zn—Ni—Cu-based ferrite materials, Patent Literature 1 proposes a ferrite sintered body formed of a Fe—Zn—Ni—Cu-based material in which X/Y≦3.0 where X is the amount of Cu at the grain boundary and Y is the amount of Cu in the grains in a fracture surface of the ferrite sintered body, and a minimum value of loss (core loss) at 20 to 140° C. is not greater than 30 kW/m3 (50 kHz, 50 mT).